IL-2 and IL-15 regulation of amino acid (aa) uptake into cells and incorporation into cellular proteins. (A) Tritiated [³H]-amino acid uptake by P14 LCMV CD8⁺ T cells activated with LCMV gp33-41 peptide for 2 days and thereafter cultured for 24 hours with the indicated concentration of IL-2 or IL-15. (B) Incorporation of [³H]-tritiated amino acid into precipitated cellular protein of antigen-activated P14 LCMV CD8⁺ T cells cultured for 24 hours in 20 ng/mL IL-2, 20 ng/mL IL-15, or medium alone. Error bars indicate SD. (C) Cellular DNA content of antigen-activated P14 LCMV CD8⁺ T cells cultured for 24 hours with medium, 20 ng/mL IL-2, or 20 ng/mL IL-15. Graphs are representative of the results of 4 or more experiments. P < .05 (estimated).